Abstracts

Rationale: We recently described a patient with hippocampal dysplasia with balloon cells (HD-bc). We raised the question of whether this is indeed an uncommon pathological finding or if it is just underdiagnosed. We describe here an additional unusual case of HD-bc and discuss here some common findings.Methods: A 49-year-old, right-handed man presented seizures characterized by epigastric aura followed by loss of consciousness and oral automatisms since 8 years old. Complex automatisms and prolonged post ictal somnolence were also reported. Seizures were occurring in a daily basis. Physical and neurological exams were normal. His MRI revealed signs of left hippocampus sclerosis; however, there was a different pattern of FLAIR and T2-weighted hyperintense signal that went all the way from the head of hippocampus to its tail (fig1). Presurgical evaluation showed interictal epileptiform discharges over the left temporal region. A left temporal seizure was recorded during video-EEG. PET scan revealed hypometabolism over the left temporal region and neuropsychological testing showed verbal memory deficits. Based on these findings and refractoriness to four AEDs, a left temporal lobectomy was performed.Results: On neuropathological examination, hematoxylin and eosin-stained (H&E) paraffin sections (5 μm) showed cell loss and gliosis in CA1, CA3 and CA4. There were balloon cells located in and surrounding the dentate gyrus (Fig. 2). There were no signs for neoplasia or inflammation. Morphological findings based the diagnosis of HD-bc.Conclusions: The diagnosis of a second case of balloon cells in the hippocampus in our center made us wonder whether it is indeed a rare pathological finding or if it not being recognized and classified as HS. The recognition of a different diagnosis besides HS may have an important role in the future, if seizure outcome after epilepsy surgery differs from the usual HS. More interesting is that MRI may give us clues that we may be dealing with a different type of pathology as in both cases there was a very strong flair hyperintense signal either involving the entire hippocampal axis or with increase hippocampal volume as in the previous case. In both cases the distribution of gliosis in CA sections was similar to the one seen in classic HS (gliosis in CA1, CA3 and CA4). In conclusion, in the setting of a strong unusual hippocampal flair/T2 hyperintense signal, the diagnosis of HD-bc should be considered and more studies are necessary to define whether this diagnosis may change the prognosis of epilepsy surgery.